Fastener element



061 10, 1944. CLARK 2,359,898

FAsTENER ELEMENT Filed Oct. 6, 1942 Patented Qct. 10, 1944 FASTENERELElVIEN T Eugene E. Clark, Providence, R. I., assignor to AmericanScrew Company, Providence, R. I., a corporation of Rhode IslandApplication October 6, 1942, Serial. No. 461,007

Claims.

This invention relates to screws and allied fasteners of the rotatabletype and more particularly to a novel form of screw head recess forengagement by various forms of screwdrivers and substitutes .therefor.

It is a general object of the present invention to provide a novel screwor fastener element provided with a recess for driving the same andadapted to accommodate several well known forms of screw-drivers.

More particularly the invention comprises a combination head recess forfastening elements adapted to accommodate the conventional Phillips typeof screw-driver, a conventional screwdriver or a small coin.

The most common form of screw for wood and machine use has heretoforebeen equipped with a transverse kerf intersecting the periphery of thehead and adapted to receive a screw-driver having a thin fiat blade.Deficiencies in the cooperating qualities of this kerf and the bladewhich resulted in slippage, burring, and other troubles led to thedevelopment of a number of so-called recesses for screw heads which werein most cases entirely confined within the peiiphery of the head toprevent marring the material into which the screws were introduced byexposed portions of the driver. recess that has become so popular thatit is beginning to entirely supplant the conventional kerf in screws fora great many purposes and industries and which is available from anumber of manufacturers is that known by the name Phillips. in Patent2,046,839, granted to H. P. Phillips et al., July 7, 1936. It includes adeep central recess and four radiating grooves adapted to cooperate withwings on a special screw-driver.

Because of the many desirable features of the Phillips recess it isspecified for a great number of purposes in various industries, but insome cases there has been one drawback to its more universal use. Itrequires a special screw-driver which on some occasions may not readiybe available, particularly in the field where repairs or adjustmentsmust often times be made. It is the purpose of the present invention toso modify the Phillips recess as to retain all of i s well knownadvantages and yet to perm t the use, where necessary, of a conventionalflat bladed screw-driver or even a small coin which may at times be moreieadily available than any form of screw-driver.

Broadly the modification consists in superimposing over one pair of theradio grooves of the Phillips recess, of a segmental, diametrically dsposed, parallel-sided kerf or groove terminating short of the peripheryof the screw head and Such a recess is shown and described One form ofbeing shallower than the central portion of the Phillips recess and theinnermost portions of the Phillips grooves over which it is applied.This groove is sufficiently wider than the Phillips grooves to eliminatetheir upper configuration and to present a slot for a conventionalscrewdriver of considerable thickness whereby the groove may alsoaccommodate a small coin.

For a better understanding of the invention reference should be had tothe following specification and the accompanying drawing wherein isdisclosed a single exemplary embodiment of the invention with theunderstanding that such changes may be made therein as fall within thescope of the appended claims without departing from the spirit of theinvention.

In said drawing:

Figure 1 is a plan view of the head of a screw or other fastening deviceequipped with the combination recess of the present invention;

Figure 2 is a longitudinal central section taken on line 2-2 of Figure1;

Figure 3 is a view similar to Figure 2 but taken at right angles theretoas on line 3-3 of Figure l; and

Figure 4 is a partial section through a cowl fastener of the type usedon present day aeroplanes showing the rotatable element thereof equippedwith the combination recess of the pzesent invention.

The invention has been shown for convenience, as applied to theso-called fiat, headed type of screw but obviously it is as well adaptedfor the several other well-known types of heads and it is not theintention to restrict the claims to any specified head shape.

Referring row to the drawing, the screw will be seen to comprise theshank I0 and the head ll conta ning the screw-driver engaging recessgenerally indicated by the reference character 12. Basically this is thePhillips recess as illustrated in the patent above identified. Thecentral portion I4 of this recess is seen to reach down into the shankof the screw and to have a blunt bottom which is generally concavetransversely to the axis of the shank and is of sufficient area andcontour to complement the lowermost end of the Phillips screw-driver.The walls of this recess are preferably eight in number and are taperedor splayed outwardly as shown at l5. Initially there are four similargrooves I6 radiating in cruciform disposition from the central recess.As seen in Figure 3 the bottoms H of these grooves slope upwardly fromthe periphery of the concave bottom and increase in width as seen inFigures 1 and 2 from the bottom toward the surface of the screw head.Each of these grooves is defined by a pair of triangular side walls Itwhich converge downwardly toward each other and unite with thesubstantially flat bottom I! just mentioned. These walls I8 merge alonglines IS with the walls l of the central recess.

To provide accommodation for a coin or a conventional screw-driver thekerf or slot 20 is provided which as shown in Figure 2 is generally ofsegmental shape and having the curved bottom wall 2| which is centrallyinterrupted because it is of less depth than the central portion of themain recess. At each end this wall intersects the surface of the head ina straight line 22 some distance inside of the head periphery. The sidewalls of the recess as shown at 23 and 24 are substantially parallel toeach other and to the axis of the shank. The total length of the slot 20is considerably greater than the combined lengths of a pair of opposedgrooves of the Phillips recess so that a relatively large sizeconventional screwdriver may be accommodated.

It will be seen that in general the slot 20 is coextensive with one pairof the Phillips grooves which are thereby materially shortened as seenat 26 in Figures 1 and 2 because their inclined bottom walls I!intersect with the-curved bottom 2| of the shallower kerf. Preferablythis kerf bottom is curved longitudinally but flat transversely as seenat 25 in Figure 3. There is, however, a sufficient radial length of eachof the reduced Phillips grooves remaining to offer a substantial drivingsurface for the cooperating wings of a Phillips screw-driver.

It will be seen that the combination recess above defined is highlyeffective for use with the standard Phillips screw-driver, with arelatively large conventional screw-driver, or with a small coin. Thepossibility of using a coin is of particular advantage when the grooveis used in the head of the rotatable fastener element 30 of an aeroplanecowl fastener such as illustrated in Figure 4, the purpose of which isto secure an outer sheet or metalplate 32 rigidly against an inner plate33 and yet to permit the rapid removal of the same for servicing themotor or other parts. The rotatable element 31 includes a transverse pin34 or like extensions adapted to cooperate with cam surfaces 35, uponbeing rotated, to draw the two sheets tightly together. The torquenecessary for rotating the element of this type of fastener isconsiderably less than that required for driving a screw in hard wood sothat a readily available coin or small washer, in the absence of a moreconventional tool, will serve to release the fastener element and permitseparation of the cowl from substantial fixed parts of the plane. Thetype of cowl fastener illustrated is only exemplary but all known formsuse a rotatable headed fastening element to which the presentcombination recess is adaptable. Since so many aeroplane claimed as newand desired to be secured by Letters Patent is:

1. A fastener element having a head and shank, a recess in the headthereof adapted to accommodate a coin, a Phillips or a conventionalscrew-driver, said recess being provided with a concave bottom extendingtransversely of the axis of the shank, and having tapering convex sidewalls diverging upwardly from the bottom to the top of the recess, fourtool receiving grooves extending radially from the recess, oneoppositely disposed pair of said grooves having side walls which mergethroughout their length with the .convex side walls of the recess andanother oppositely disposed pair forming a parallel sided segmental kerfsized to fit a coin but of less length than the diameter of the head.

2. A fastening element having a head and shank, a recess in the headthereof adapted to accommodate a coin, a Phillips" or a conventionalscrew-driver, said recess comprising a central depression extendingtransversely of the axis of the shank and into the shank and two pairsof opposing grooves each extending radially from the depression, each ofthe grooves of one pair tapering in width from the depression outwardly,having fiat tapered side walls and a flat tapered bottom wall, the otherpair of grooves each having flat, parallel side walls and a bottom wallcurved in the direction of its length but of unlform width.

motor parts are secured with screws equipped may be formed by a cuttingor sawing operation.

,Having thus described the invention, what is 3. In a fastening elementhaving a head and a shank, a recess comprising a centrally spaced mainslot terminating short of the periphery of the head, the side walls ofthe said slot being parallel to each other and to the shank axis, theintersections of the said walls and the bottom of the slot beingarcuate, the arcuate bottom wall intersecting the top of the head at theends of the slot, a central well in said head having a concave bottomtransverse to said axis and below the bottom of said slot, two pairs oftool receiving grooves extending radially from the well and having sidewalls converging from top to bottom, one pair of said grooves beingcoextensive with said slot and deeper than the same.

4. In a fastening element having a substantially flat head and a shank,a diametrically disposed slot in the head sized to accommodate a coinand terminating short of the periphery of the head, the bottom wall ofthe slot being arcuate, the arcuate bottom wall intersecting the top ofthe head at the ends of the slot, a central well in said head having aconcave bottom transverse to said axis and below the bottom of saidslot, two pairs of tool receiving grooves extending radially from thewell and having side walls converging from top to bottom, one pair ofsaid grooves being coextensive with said slot and deeper than the same.

5. A fastener element comprising a shank and a head, said head having acentral recess bounded by tapering side walls diverging from the bottomto the top thereof, cruciform tool blade receiving grooves extendingradially from and communieating at their inner extremities with saidrecess, said grooves-being defined by oppositely disposed side wallswhich merge with the side walls of said recess and diverge upwardly, atleast two of the oppositely disposed radial grooves having relativelyshallow radial extensions to accommodate a relatively wide turningblade.

EUGENE E. CLARK.

